Nickel-chromium alloys are known for their capability of affording various degrees of resistance to a host of diverse corrosive environments. For this reason such alloys have been widely used in sundry applications, from superalloys in aerospace to marine environments. One particular area of utility has been in glass vitrification furnaces for nuclear wastes. The alloy that has been conventionally employed is a nominal 60Ni-30Cr-10Fe composition which is used as the electrode material submerged in the molten glass and for the pouring sout. It has also been used for the heaters mounted in the roof of the furnace and for the effluent containment hardware.
By reason of its strength and corrosion resistance in such an environment, the 60Ni-30Cr-10Fe alloy provides satisfactory service for a period of circa 2 years, sometimes less sometimes more. It normally fails by way of sulfidation and/or oxidation attack, probably both. It would thus be desirable if an alloy for such an intended purpose were capable of offering an extended service life, say 3-5 years or more. This would not only require a material of greatly improved sulfidation/oxidation resistance, but also material that possessed high stress rupture strength characteristics at such operating temperatures, and also good tensile strength, toughness and ductility, the latter being important in terms of formability operations. To attain the desired corrosion characteristics at the expense of strength and other properties would not be a desired panacea.